U.S. patent application number 12/096879 was filed with the patent office on 2010-01-28 for method for determining a variable.
Invention is credited to Ruediger Jordan.
Application Number | 20100019951 12/096879 |
Document ID | / |
Family ID | 41568148 |
Filed Date | 2010-01-28 |
United States Patent
Application |
20100019951 |
Kind Code |
A1 |
Jordan; Ruediger |
January 28, 2010 |
METHOD FOR DETERMINING A VARIABLE
Abstract
A method for determining a variable associated with an object,
the object having a plurality of points suitable for reflecting
measuring signals, a probability of reflections occurring at these
points is taken into account for evaluating at least one measuring
signal.
Inventors: |
Jordan; Ruediger;
(Stuttgart, DE) |
Correspondence
Address: |
KENYON & KENYON LLP
ONE BROADWAY
NEW YORK
NY
10004
US
|
Family ID: |
41568148 |
Appl. No.: |
12/096879 |
Filed: |
August 18, 2006 |
PCT Filed: |
August 18, 2006 |
PCT NO: |
PCT/US06/65458 |
371 Date: |
February 20, 2009 |
Current U.S.
Class: |
342/109 ;
342/159 |
Current CPC
Class: |
G01S 7/40 20130101; G01S
13/931 20130101; G01S 13/58 20130101; G01S 2013/9321 20130101 |
Class at
Publication: |
342/109 ;
342/159 |
International
Class: |
G01S 13/58 20060101
G01S013/58; G01S 13/00 20060101 G01S013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 14, 2005 |
DE |
10 2005 049 129.4 |
Claims
1-11. (canceled)
12. A method for determining at least one variable associated with
an object, the method comprising: evaluating at least one measuring
signal by taking into account a probability of reflections, the
object having a plurality of points suitable for reflecting
measuring signals to provide the reflections, occurring at the
points.
13. The method of claim 12, wherein a relative location of the
object is determined.
14. The method of claim 12, wherein a relative speed of the object
is determined.
15. The method of claim 12, wherein the at least one measuring
signal is weighted according to the probability of occurrence.
16. The method of claim 12, wherein the variable of the object to
be determined is determined as a function of the probability
occurrence.
17. The method of claim 12, wherein a consolidated measured value
is formed from the at least one measuring signal.
18. A device for determining at least one variable associated with
an object, comprising: an evaluating arrangement to evaluate at
least one measuring signal by taking into account a probability of
reflections, the object having a plurality of points suitable for
reflecting measuring signals to provide the reflections, occurring
at the points.
19. The device of claim 18, wherein a relative location of the
object is determined.
20. The device of claim 18, wherein a relative speed of the object
is determined.
21. The device of claim 18, wherein the at least one measuring
signal is weighted according to the probability of occurrence.
22. The device of claim 18, wherein the variable of the object to
be determined is determined as a function of the probability
occurrence.
23. The device of claim 18, wherein a consolidated measured value
is formed from the at least one measuring signal.
24. The device of claim 18, which has a sensor for receiving the at
least one measuring signal reflected by the object.
25. The device of claim 18, which has a transmitter for
transmitting a signal and a sensor for receiving the at least one
measuring signal reflected by the object.
26. A computer-readable medium having program code executable by a
processor, comprising: a computer code arrangement for determining
at least one variable associated with an object, by evaluating at
least one measuring signal by taking into account a probability of
reflections, the object having a plurality of points suitable for
reflecting measuring signals to provide the reflections, occurring
at the points.
27. The computer-readable medium of claim 26, wherein a relative
location of the object is determined.
28. The computer-readable medium of claim 26, wherein a relative
speed of the object is determined.
29. The computer-readable medium of claim 26, wherein the at least
one measuring signal is weighted according to the probability of
occurrence.
30. The computer-readable medium of claim 26, wherein the variable
of the object to be determined is determined as a function of the
probability occurrence.
31. The computer-readable medium of claim 26, wherein a
consolidated measured value is formed from the at least one
measuring signal.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method and a device for
determining a variable associated with an object, and a computer
program and a computer program product.
BACKGROUND INFORMATION
[0002] A radar sensor typically measures maximum values of
temporary reflections on objects. However, such reflections do not
describe fixed points on the object, but instead migrate and jump
as a function of the viewing angle. Even very small changes in the
viewing angle are sufficient to obtain a different reflection
response. For objects which are larger than the resolution
capability of the radar sensor, multiple reflections may be
measured at the same time. Clustering of the reflections using a
fixed aperture (for example, 2 m*8 m) and averaging of measured
values is a current practice. To determine a rear edge of the
object, the reflection which is spatially closest is selected. This
may result in apparent motions of the object when the reflection
jumps on the object, or when another portion of the object returns
the reflection more strongly. When traveling past a vehicle, it is
also problematic when the reflection travels on an outer edge of
the object toward the host vehicle. In the worst case scenario,
this apparent motion of the object may result in spurious
triggering of a predictive safety system (PSS).
SUMMARY OF THE INVENTION
[0003] A method having the features described herein, a device
having the features described herein, a computer program having the
features described herein, and a computer program product having
the features described herein are described herein.
[0004] In the method according to the present invention for
determining at least one variable or state variable associated with
an object, the object having a plurality of points suitable for
reflecting measuring signals, a probability of reflections
occurring at these points is taken into account for evaluating at
least one measuring signal.
[0005] The device according to the present invention for
determining at least one variable associated with an object, the
object having a plurality of points which are suitable for
reflecting a measuring signal. The device is designed to take into
account a probability of reflections occurring at these points in
order to evaluate at least one measuring signal.
[0006] Advantageous embodiments result from the description
herein.
[0007] The present invention further relates to a computer program
having a program code arrangement for carrying out all the steps of
a method according to the present invention when the computer
program is executed on a computer or an appropriate computing unit,
in particular a unit in a device according to the present
invention.
[0008] The exemplary embodiments and/or exemplary methods of the
present invention further relates to a computer program product
having a program code arrangement which is stored on a
computer-readable data carrier for carrying out all the steps of a
method according to the present invention when the computer program
is executed on a computer or an appropriate computing unit, in
particular a unit in a device according to the present
invention.
[0009] The exemplary embodiments and/or exemplary methods of the
present invention employs a statistical approach which takes into
account the probability of points reflecting on an elongated
object, for example a vehicle. Incoming measured values are
weighted differently, depending on the particular probability of
their occurrence at that time. In turn, this is a function of the
variable, in particular a relative location or a relative speed,
which is associated with the object. For this purpose, the
probability of occurrence, which is deduced from a comprehensive
reflection model for the object, is provided.
[0010] So-called radar reflection modeling is made possible by the
present invention. Measurements of the surroundings allow a
location and/or speed of an object present in the surroundings of
the device to be determined. A signal is transmitted, and is
reflected from a point on the object as at least one measuring
signal and is received by a sensor. The device may be situated in a
vehicle and used for monitoring objects in the surroundings of this
vehicle.
[0011] Lastly, from all the incoming measuring signals from the
object, a consolidated measured value may be formed which optimally
describes the sought physical variables of the object. The
consolidated measured value may be further processed in a
subsequent tracking algorithm.
[0012] By use of a statistical distribution of the probability of
occurrence and thus of radar reflections on the object, a location
or speed determination, and therefore an estimation of the state of
the object, may be carried out more accurately and reliably.
Apparent motions of the object which are caused by reflection
motions on the object and which thus corrupt a measurement result
may be minimized by using the method.
[0013] Furthermore, motions in the longitudinal and transverse
directions relative to the device may be taken into account.
[0014] Separate treatment of each variable or measurement
dimension, such as distance, speed, or lateral offset of the
object, may facilitate ease of operation of the model.
[0015] In the evaluation of measuring signals provided by angular
resolution sensors or radar sensors, apparent motions therefore do
not occur on average in the longitudinal or transverse direction
when vehicles are passed; i.e., the estimated location of the
object does not move along an outer edge of the object, but instead
describes the center of a rear edge of the object on average.
[0016] The method may be used in predictive safety systems (PSS2)
and adaptive cruise control systems (ACC plus).
[0017] Further advantages and embodiments of the invention result
from the description and the accompanying drawings.
[0018] It is understood that the features mentioned above and to be
described below may be used not only in the particular stated
combination, but also in other combinations or alone, without
departing from the scope of the exemplary embodiments and/or
exemplary methods of the present invention.
[0019] The exemplary embodiments and/or exemplary methods of the
present invention is schematically illustrated on the basis of one
exemplary embodiment in the drawings, and is described in detail
below with reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 shows a diagram of a probability of occurrence used
for a distance measurement.
[0021] FIG. 2 shows a diagram of a probability of occurrence used
for a speed measurement.
[0022] FIG. 3 shows, in a schematic illustration, an example of an
evaluation of a turntable measurement.
[0023] FIG. 4 shows a diagram of a vehicle extension model.
[0024] FIG. 5 shows a diagram of a distribution of reflections.
[0025] FIG. 6 shows a diagram of a reflection point shift.
DETAILED DESCRIPTION
[0026] The figures are described in an interrelated and integrated
manner, with use of the same reference numerals to denote identical
components.
[0027] The measurement of a correct distance from a rear edge as a
point 2 on an object 4, which in this case takes the form a
vehicle, is based on the probability of occurrence 6 or the
probability distribution of radar reflections shown in the diagram
in FIG. 1, which is plotted along ordinate 8 over the abscissa 10
for the distance.
[0028] One reason for an asymmetry in the probability of occurrence
6 is that the rear edge of object 4 is not always correctly
estimated. For example, when measuring objects 4 for the first
time, it may happen that the front edge is measured instead of the
rear edge. The probability that the actual rear edge is thus
located farther backward, corresponding to a smaller distance, is
higher than the probability that the actual rear edge is located
farther forward, corresponding to a larger distance.
[0029] A measurement of a correct speed of object 4 is based on the
probability of occurrence 12 of radar reflections shown in the
diagram in FIG. 2, which is likewise plotted along ordinate 8 over
abscissa 10 for the distance.
[0030] In this case, one reason for an asymmetry is that the rear
edge as point 2 on object 4 is not always precisely estimated, but
that any point and thus any point 2 on object 4 is able to provide
a correct speed measurement. Measured values of the speed of the
rear edge are generally more accurate than the measured values for
points on object 4 situated farther forward, since reflections from
the rear edge are more powerful.
[0031] For measuring a lateral offset of object 4, the center of
the rear edge is estimated in the transverse direction of the
object. However, it must be kept in mind that an accurate position
of the reflection depends greatly on a viewing angle for object
4.
[0032] Detailed tests on objects 14, in a a vehicle schematically
illustrated in FIG. 3, which are measured on a turntable in at
least two spatial directions x, y 16, 18 have shown that a measured
angle on average is situated at points 20, 22, 24, which are
located at the smallest relative distance from a sensor. In the
frontal view, a center is measured as point 20 of the vehicle. In
large viewing angle ranges, only corners are measured as points 22,
24 of the vehicle. Smooth transitions result between same.
[0033] Corresponding to these findings, a dimensional model 26,
shown in FIG. 4, has been developed for vehicles in first and
second spatial directions x, y 28, 30. The model is composed of a
rectangular body 32 having a circular curvature 34. Since in road
traffic the rear edge is generally measured as point 33 on an
object 35 via dimensional model 26, it is sufficient to model the
latter. The objective is to estimate, from a sensor 36, center 37
of the rear edge as a function of a viewing angle .phi. 38. This
results in a probability of occurrence of a distribution of
reflections 40 at various points, which is a function of viewing
angle p 38 of object 35 or the vehicle.
[0034] The relative position of object 35, as shown in FIG. 4, may
be used to compute the most probable shift .DELTA.dy 42 of
reflection 40 with respect to center 37 of the rear edge as point
33 of object 35.
[0035] FIG. 5 shows three examples of distributions 44, 46, 48 for
reflections, which are plotted along an ordinate 50 over an
abscissa 52 for the viewing angle T 38 (FIG. 4).
[0036] However, an estimation of relative viewing angles 54 or 56
according to FIG. 4 represents a problem, since these variables are
not directly measured by sensor or the radar sensor. However, these
variables may be estimated using the relative motion in x and y
directions 28, 30, via a course of the roadway or based on an
instantaneous course of the observing sensor 36 itself. However,
the estimate becomes more unreliable the greater the distance of
sensor 36 from object 35. This must therefore be taken into
account, since the estimated shift of reflections 40 is less of a
factor at greater distances.
[0037] Using theoretical probability considerations, the set of
curves 58 shown in the diagram in FIG. 6 is obtained for shifts of
reflections 40 (FIG. 4). Each of these curves is plotted for
various distances dy 60 in y direction 28 according to FIG. 4 in
the direction of distances dx 62 in x direction 28 according to
FIG. 4, which are plotted along an ordinate 64, over the most
probable shift .DELTA.dy 42 along abscissa 66. For this purpose, as
a rule, multiple viewing angles .phi. 38 as well as measured values
for distances dx 62 and dy 60 are provided by sensor 36.
[0038] All measured values are weighted using the probability of
occurrence such that the latter describes the sought physical
variable. For determining a lateral offset, measuring signals that
primarily also lie on the rear edge are physically provided with
the most weight.
[0039] A consolidated pseudo-measured value is formed from the
probability of occurrence, which describes the currently most
probable speed of object 35 and the most probable position of
center 37 of the rear edge of object 35. This pseudo-measured value
may be further processed with the assistance of common tracking
algorithms, using Kalman filters, for example.
* * * * *